TICK-TOCK-HEDGEHOG: Hedgehog signalling controls the liver circadian clock and vice versa

The Hedgehog signalling (HH-) pathway presents an evolutionary highly conserved cascade. Being one of the crucial modulators of embryogenesis and tissue differentiation its role in adult healthy organs like liver is often neglected. Interestingly, recent analyses identified the hedgehog signalling as a putative modulator of the circadian clock, which, at the molecular level, is organised by different self-regulatory transcriptional-translational feedback loops, comprising the so cold Core Clock Genes (CCGs). As an extensive biological process the clock is tightly linked to the elements of cell cycle control and intracellular signalling pathways, so the hedgehog-clock association seems to be reasonable. However, so far no data have been reported.